The commissioner’s office has decided not to discipline Alex Rodriguez in light of its investigation into whether he lied about his use of performance-enhancing drugs in a meeting with baseball officials in March, according to people in baseball with knowledge of the matter.

Jay K. Reisinger, a lawyer for Rodriguez, declined to comment. The people within baseball spoke on the condition of anonymity because they were discussing an internal investigation.

As part of the investigation, baseball investigators interviewed Angel Presinal, a Dominican trainer who has been barred from major league clubhouses since 2002 after being linked to an incident involving performance-enhancing drugs. The interview of Presinal, who has trained Rodriguez and dozens of major league players, yielded little information about Rodriguez’s possible use of banned substances.

The New York Times reported in May that members of baseball’s department of investigations had contacted Selena Roberts, the author of “A-Rod: The Many Lives of Alex Rodriguez,” and several of Rodriguez’s associates to determine whether Rodriguez had used performance-enhancing drugs for a longer period than he admitted.

The investigation began shortly after Rodriguez met with the investigators and baseball’s top labor lawyer, Rob Manfred, in March to question him after it was revealed that he had tested positive for steroids. He subsequently admitted publicly that he used a substance he referred to as “boli” from 2001 to 2003. In the meeting with the baseball officials, Rodriguez reiterated that he used boli from 2001 to 2003 and said that he had never received substances from Presinal.

Concerns about the truthfulness of Rodriguez’s statements grew in the commissioner’s office in April, after Roberts’s book was published. It contained assertions that Rodriguez used several different steroids under the supervision of Presinal and had human growth hormone in his possession in 2004.

The investigation proved difficult for the commissioner’s office, but it also showed that its investigations department was willing to try to develop evidence against one of the game’s premier stars, particularly in its effort to interview Presinal. Many of the accusations in the book were not damning and were based on anonymous sources. Other accusations were several years old, and Roberts declined to cooperate with the investigation. The baseball investigators have little power to compel witnesses who do not work for baseball to speak with them.